Microstructural changes induced in borosilicate glasses by 1 MeV electrons

Radiation damage to borosilicate glass has been studied using a high voltage electron microscope to simultaneously generate and image structural changes At low doses and dose rates (φ ? 5 × 10²⁴ electrons m^-2, F ? 5 × 10²² el m^-2 s^-1), ionic depletion generates a new crystalline phase rich in S₁O₂ For incubation doses exceeding 5 × 10²⁴ electrons m^-2, gas bubbles are observed High damage rates are necessary for bubble nucleation though not for their subsequent growth The critical nucleation flux increases rapidly with irradiation temperature, whereas the gas precipitation efficiency remains constant above 300 K.